Extra mesoporous Y zeolite

ABSTRACT

This invention relates to the composition and synthesis of an Extra Mesoporous Y (or “EMY”) zeolite and its use in the catalytic conversion of organic compounds. In particular, this invention relates to a Y-type framework zeolite possessing a high large mesopore pore volume to small mesopore pore volume ratio. The novel zeolite obtained provides beneficial structural features for use in petroleum refining and petrochemical processes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional application which claims the benefit of U.S.Non-Provisional application Ser. No. 12/584,376 filed Sep. 4, 2009 whichclaims the benefit of U.S. Provisional Application No. 61/192,391 filedSep. 18, 2008, and which are both incorporated by reference herein intheir entirety.

FIELD

This invention relates to the composition and synthesis of an ExtraMesoporous Y (“EMY”) zeolite and its use in the catalytic conversion oforganic compounds.

BACKGROUND

Zeolitic materials, both natural and synthetic, have been demonstratedin the past to have utility as adsorbent materials and to have catalyticproperties for various types of hydrocarbon conversion reactions.Certain zeolitic materials are ordered, porous crystallinemetallosilicates having a definite crystalline structure as determinedby X-ray diffraction, within which there are a large number of smallercavities which may be interconnected by a number of still smallerchannels or pores. These cavities and pores are uniform in size within aspecific zeolitic material. Since the dimensions of these pores are suchas to accept for adsorption molecules of certain dimensions whilerejecting those of larger dimensions, these materials have come to beknown as “molecular sieves” and are utilized in a variety of ways totake advantage of these properties.

Such molecular sieves, both natural and synthetic, include a widevariety of positive ion-containing crystalline silicates. Thesesilicates can be described as a rigid three-dimensional framework ofSiO₄ tetrahedra and optionally tetrahedra of a Periodic Table Group IIIAelement oxide, e.g., AlO₄, in which the tetrahedra are cross-linked bythe sharing of oxygen atoms whereby the ratio of the total Group IIIAelement and silicon atoms to oxygen atoms is 1:2. The electrovalence ofthe tetrahedra containing the Group IIIA element is balanced by theinclusion in the crystal of a cation, for example an alkali metal or analkaline earth metal cation. This can be expressed wherein the ratio ofthe Group IIIA element, e.g., aluminum, to the number of variouscations, such as Ca/2, Sr/2, Na, K or Li, is equal to unity. One type ofcation may be exchanged either entirely or partially with another typeof cation utilizing ion exchange techniques in a conventional manner. Bymeans of such cation exchange, it has been possible to vary theproperties of a given silicate by suitable selection of the cation.

Prior art techniques have resulted in the formation of a great varietyof synthetic zeolites. Many of these zeolites have come to be designatedby letter or other convenient symbols, as illustrated by zeolite A (U.S.Pat. No. 2,882,243); zeolite X (U.S. Pat. No. 2,882,244); zeolite Y(U.S. Pat. No. 3,130,007); zeolite ZK-5 (U.S. Pat. No. 3,247,195);zeolite ZK-4 (U.S. Pat. No. 3,314,752); zeolite ZSM-5 (U.S. Pat. No.3,702,886); zeolite ZSM-11 (U.S. Pat. No. 3,709,979); zeolite ZSM-12(U.S. Pat. No. 3,832,449), zeolite ZSM-20 (U.S. Pat. No. 3,972,983);ZSM-35 (U.S. Pat. No. 4,016,245); zeolite ZSM-23 (U.S. Pat. No.4,076,842); zeolite MCM-22 (U.S. Pat. No. 4,954,325); and zeolite MCM-35(U.S. Pat. No. 4,981,663), merely to name a few.

Type “Y” zeolites are of the faujasite (“FAU”) framework type which isdescribed in Atlas of Zeolitic Framework Types (Ch. Baeriocher, W. M.Meier, and D. H. Olson editors, 5th Rev, Ed., Elsevier Science B.V.,2001) and in the pure crystalline form are comprised ofthree-dimensional channels of 12-membered rings. The crystalline zeoliteY is described in U.S. Pat. No. 3,130,007. Zeolite Y and improved Y-typezeolites such as Ultra Stable Y (“USY” or “US-Y”) (U.S. Pat. No.3,375,065) not only provide a desired framework for shape selectivereactions but also exhibit exceptional stability in the presence ofsteam at elevated temperatures which has resulted in this zeolitestructure being utilized in many catalytic petroleum refining andpetrochemical processes. Additionally, the three-dimensional porechannel structure of the faujasite framework zeolites, such as theY-type zeolites, in combination with their relatively good ability toretain a high surface area under severe hydrothermal conditions andtheir generally low cost to manufacture makes these zeolites a preferredcomponent for Fluid Catalytic Cracking (“FCC”) catalysts in petroleumrefining and petrochemical processes.

In a pure zeolite crystal, the pore diameters are typically in the rangeof a few angstroms in diameter. Y-type zeolites exhibit pore diametersof about 7.4 Angstroms (Å) in the pure crystal form. However, inmanufacture, defects in the crystalline structure and in particular inthe inter-crystal interfaces occur in the crystalline structure ofzeolites, including the Y-type zeolites. Additionally, due to certainmethods of preparations and/or use, both wanted and unwanted structuralmodifications can be made to the zeolite crystal. It is these “defects”which lead to specific properties of the zeolite which may havebeneficial properties when utilized in catalytic processes.

The conventional Ultra Stable Y (USY) zeolites prepared by mild steamcalcination, as taught by U.S. Pat. No. 3,375,065, contains mesopores inthe 30 to 50 Å regions. Pores with pore diameters in the 30 to 50 Årange are herein defined as “Small Mesopores”. Another type of Y zeolitestabilization utilizes chemical processes to remove framework aluminumatoms. One example of Y zeolites obtained from such processes is LZ-210(U.S. Pat. No. 4,711,770). In LZ-210, the vacancies of removed aluminumatoms are replaced by silicon atoms, therefore preserving nearly perfectcrystal structure of Y zeolite with very little formation of mesopores.In FCC applications, however, such perfect Y zeolite, i.e., withoutmesopores, leads to low conversions of heavy hydrocarbons. As the FCCfeed stream is getting heavier, it is more desirable to have a zeolitewith more mesopores in the large mesoporous region. Here we define“Large Mesopores” as pores with pore diameter in the greater than 50 to500 Å regions. It is believed that zeolites with large mesopores canenhance conversions of heavy hydrocarbons. A problem that exists in theindustry is that many Y-type zeolites (e.g., Na—Y zeolites), whilewidely used in the industry, exhibit a “peak” in the small mesoporerange (30 to 50 Å pore diameters) while exhibiting no significant porevolume associated with the large mesopore range (50 to 500 Å porediameters). Conversely, other Y-type zeolites (e.g., USY zeolites),exhibit a significant “peak” in the small mesopore range (30 to 50 Åpore diameters) when some large mesopores are present.

Therefore, what is needed in the art is an improved Y-type zeolite whichpossesses an improved large mesoporous volume to small mesoporous volumeratio structure while suppressing the magnitude of the “small mesoporepeak” associated with pores measured in the small mesopore range (30 to50 Å pore diameters)

SUMMARY

The present invention includes an extra mesoporous Y zeolite (termedherein as “EMY” zeolite) which has improved mesoporous properties over Yzeolites of the prior art, as well as a method of making the zeolite andits use in catalytic hydrocarbon processing.

One embodiment of the present invention is a Y zeolite comprising aLarge Mesopore Volume of at least about 0.03 cm³/g and a Small MesoporePeak of less than about 0.15 cm³/g. In a preferred embodiment, thezeolite has a unit cell size from about 24.37 Angstroms to about 24.47Angstroms. In an even more preferred embodiment, the zeolite has aLarge-to-Small Pore Volume Ratio of at least about 4.0. Definitions ofthese terms are provided herein.

In a preferred embodiment of the present invention, the values for theLarge Mesopore Volume of the zeolite and the Small Mesopore Peak of thezeolite above are measured in the as-fabricated zeolite (i.e., thezeolite obtained after high temperature steam calcining). In even morepreferred embodiments, the zeolite of the present invention has aLarge-to-Small Pore Volume Ratio of at least about 5.0, a Small MesoporePeak of less than about 0.13 cm³/g, and a Large Mesopore Volume of atleast 0.05 cm³/g.

Additionally, in a preferred embodiment of the present invention is amethod of making an extra mesoporous zeolite, comprising:

a) ammonium exchanging a Na—Y zeolite to obtain a zeolite precursor witha Na₂O content from about 2 to about 5 wt %; and

b) subjecting the precursor to a high temperature steam calcination at atemperature from about 1200° F. to about 1500° F. wherein thetemperature of the zeolite precursor is within 50° F. of the hightemperature steam calcination temperature in less than 5 minutes;

wherein the zeolite has a Large Mesopore Volume of at least about 0.03cm³/g, and a Small Mesopore Peak of less than about 0.15 cm³/g.

In other preferred embodiments of the method of making, the Na₂O contentof the zeolite precursor is held to within from about 2.2 to about 4 wt% on a dry basis. In other preferred embodiments, the temperature of thezeolite precursor during the high temperature steam calcination step isbrought within 50° F. of the high temperature steam calcinationtemperature in less than 2 minutes.

Additionally, in a preferred embodiment of the present invention is aprocess for using an extra mesoporous zeolite for conversion of ahydrocarbon-containing stream, comprising:

a) contacting the hydrocarbon-containing feedstream with a Y zeolite ina petroleum refining process; and

b) producing at least one product stream which has a lower averagemolecular weight than the hydrocarbon-containing feedstream;

wherein the zeolite has a Large Mesopore Volume of at least about 0.03cm³/g, and a Small Mesopore Peak of less than about 0.15 cm³/g.

In preferred embodiments, the petroleum refining process is selectedfrom a catalytic cracking process, a fluidized catalytic crackingprocess, a hydrocracking process, a hydrodesulfurization process, areforming process, an alkylation process, an oligomerization process, adewaxing process, and an isomerization process.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a BJH N₂ Desorption Plot of a USY zeolite from a commerciallyavailable ammonium-Y zeolite.

FIG. 2 is a BJH N₂ Desorption Plot of the USY zeolite of FIG. 1 after ithas been subjected to ion exchange/calcination steps and long-termdeactivation steaming at 1400° F. for 1 hours.

FIG. 3 is a BJH N₂ Desorption Plot of an embodiment of an ExtraMesoporous Y (“EMY”) zeolite of the present invention.

FIG. 4 is a BJH N₂ Desorption Plot of an embodiment of an ExtraMesoporous Y (“EMY”) zeolite of the present invention after it has beensubjected to ion-exchange/calcination steps and long-term deactivationsteaming at 1400° F. for 16 hours.

FIG. 5 is a BJH N₂ Desorption Plot of an EMY zeolite precursor.

FIG. 6 is a BJH N₂ Desorption Plot of an EMY zeolite precursor that hasbeen high temperature steam calcined at 1000° F. for 1 hour in 100%steam wherein the EMY zeolite precursor temperature during the hightemperature steam calcination was raised to within 50° F. of the hightemperature steam calcination temperature within 2 minutes.

FIG. 7 is a BJH N₂ Desorption Plot of an EMY zeolite precursor that hasbeen high temperature steam calcined at 1200° F. for 1 hour in 100%steam wherein the EMY zeolite precursor temperature during the hightemperature steam calcination was raised to within 50° F. of the hightemperature steam calcination temperature within 2 minutes.

FIG. 8 is a BJH N₂ Desorption Plot of an EMY zeolite precursor that hasbeen high temperature steam calcined at 1300° F. for 1 hour in 100%steam wherein the EMY zeolite precursor temperature during the hightemperature steam calcination was raised to within 50° F. of the hightemperature steam calcination temperature within 2 minutes.

FIG. 9 is a BJH N₂ Desorption Plot of an EMY zeolite precursor that hasbeen high temperature steam calcined at 1400° F. for 1 hour in 100%steam wherein the EMY zeolite precursor temperature during the hightemperature steam calcination was raised to within 50° F. of the hightemperature steam calcination temperature within 2 minutes.

FIG. 10 is a BJH N₂ Desorption Plot of an EMY zeolite precursor that hasbeen high temperature steam calcined at 1500° F. for 1 hour in 100%steam wherein the EMY zeolite precursor temperature during the hightemperature steam calcination was raised to within 50° F. of the hightemperature steam calcination temperature within 2 minutes.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The Extra Mesoporous Y (“EMY”) zeolite of the present invention producesa Y-type zeolite with a suppressed “small mesopore peak” that iscommonly found associated with in the “small mesopores” (30 to 50 Å porediameters) of commercial Y-type zeolites, while maintaining asubstantial volume of pores in the “large mesopores” (greater than 50 to500 Å pore diameters) of the zeolite. International Union of Pure andApplied Chemistry (“IUPAC”) standards defines “mesopores” as having porediameters greater than 20 to less than 500 Angstroms (Å). However, thestandard nitrogen desorption measurements as used herein do not providepore volume data below about 22 Å. Additionally, since the “smallmesopore peak” found in Y zeolites are substantially confined betweenthe 30 and 50 Å ranges, it is sufficient to define the measurablemesoporous pore diameter range for the purposes of this invention aspore diameters from 30 to 500 Angstroms (Å).

Therefore, as utilized herein, the terms “Small Mesopore(s)” or “SmallMesoporous” are defined as those pore structures in the zeolite crystalwith a pore diameter of 30 to 50 Angstroms (Å). Similarly, the terms“Large Mesopore(s)” or “Large Mesoporous” as utilized herein are definedas those pore structures in the zeolite crystal with a pore diameter ofgreater than 50 to 500 Angstroms (Å). The terms “Mesopore(s)” or“Mesoporous” when utilized herein alone (i.e., not in conjunction with a“small” or “large” adjective) are defined herein as those porestructures in the zeolite crystal with a pore diameter of 30 to 500Angstroms (Å). Unless otherwise noted, the unit of measurement used formesoporous pore diameters herein is in Angstroms (Å).

The term “Small Mesopore Volume” or “Small Mesoporous Volume” of amaterial as used herein is defined as the total pore volume of the poresper unit mass in the Small Mesopore range as measured and calculated byASTM Standard D 4222 “Determination of Nitrogen Adsorption andDesorption Isotherms of Catalysts and Catalyst Carriers by StaticVolumetric Measurements”; ASTM Standard D 4641 “Calculation of Pore SizeDistributions of Catalysts from Nitrogen Desorption Isotherms”; and “TheDetermination of Pore Volume and Area Distributions in PorousSubstances, L Computations from Nitrogen Isotherms”, by Barrett, E. P.;Joyner, and Halenda, P. P.; Journal of American Chemical Society; vol.73, pp. 373-380 (1951), all of which are incorporated herein byreference. Unless otherwise noted, the unit of measurement for mesoporevolume is in cm³/g.

The term “Large Mesopore Volume” or “Large Mesoporous Volume” of amaterial as used herein is defined as the total pore volume of the poresper unit mass in the Large Mesopore range as measured and calculated byASTM Standard D 4222 “Determination of Nitrogen Adsorption andDesorption Isotherms of Catalysts and Catalyst Carriers by StaticVolumetric Measurements”; ASTM Standard D 4641 “Calculation of Pore SizeDistributions of Catalysts from Nitrogen Desorption isotherms”; and “TheDetermination of Pore Volume and Area Distributions in PorousSubstances, I. Computations from Nitrogen Isotherms”, by Barrett, E. P.;Joyner, L. S.; and Halenda, P. P.; J. Amer. Chem. Soc.; vol. 73, pp.373-380 (1951). Unless otherwise noted, the unit of measurement formesopore volume is in cm³/g.

The term “Large-to-Small Pore Volume Ratio” or “LSPVR” of a material asused herein is defined as the ratio of the Large Mesopore Volume to theSmall Mesopore Volume (dimensionless).

The term “BJH N₂ Desorption Plot” as used herein is defined as a plot ofthe change in unit volume of a mesoporous material as a function of thepore diameter of the mesoporous material. Herein, the “BJH N₂ DesorptionPlot” is shown as the pore volume calculated as dV/d log D (in cm³/g)vs. the pore diameter (in nanometers) as determined by the ASTM StandardD 4222, ASTM Standard D 4641, and “The Determination of Pore Volume andArea Distributions in Porous Substances, L Computations from NitrogenIsotherms”, by Barrett, E. P.; Joyner, L. S.; and Halenda, P. P.;Journal of American Chemical Society; vol. 73, pp. 373-380 (1951),(i.e., the “BJH method” for calculating the pore distribution of aporous substance) as referenced in the definitions above. The BJH N₂Desorption Plot should be generated from approximately 15 to 30 datapoints at approximately equidistant positions on a logarithmic x-axis ofthe pore diameter (nanometers) between the values of 3 to 50 nanometers(30 to 500 Å). The pore volume value on the y-axis of the plot iscommonly calculated in industry equipment as an interpolated value ofthe incremental change in volume, dV (where V is in cm³, and dV is incm³) divided by the incremental change in the log of the pore diameter,d log D (where D is in nanometers, and d log D is unitless) and isadjusted to the unit weight of the sample in grams. Therefore, the “porevolume” (which is the common term utilized in the industry) as shown onthe y-axis of the BJH N₂ Desorption Plot may be more appropriatelydescribed as an incremental pore volume per unit mass and is expressedherein in the units cm³/g. It should be noted that the “pore volume”value on the y-axis of the BJH N₂ Desorption Plot is not synonymous withthe “Small Mesopore Volume” and “Large Mesopore Volume” as describedabove which are calculated unit pore volumes over a range of porediameters. However, these calculations and terms as used herein arefamiliar to those of skill in the art. All measurements and data plotsas utilized herein were made with a Micromeritics® Tristar 3000®analyzer.

The term “Small Mesopore Peak” for a material as used herein is definedas the maximum pore volume value calculated as dV/d log D (y-axis) on aBJH N₂ Desorption Plot as described above (pore volume vs. porediameter) between the 30 Å and 50 Å pore diameter range (x-axis). Unlessotherwise noted, the unit of measurement for the small mesopore peak isin cm³/g.

The term “Large Mesopore Peak” for a material as used herein is definedas the maximum pore volume value calculated as dV/d log D (y-axis) on aBJH N₂ Desorption Plot as described above (pore volume vs. porediameter) between the 50 Å and 500 Å pore diameter range (x-axis).Unless otherwise noted, the unit of measurement for the large mesoporepeak is in cm³/g.

The term “BET Surface Area” for a material as used herein is defined asthe surface area as determined by ASTM Specification D 3663. Unlessotherwise noted, the unit of measurement for surface area is in m²/g.

The term “Unit Cell Size” for a material as used herein is defined asthe unit cell size as determined by ASTM Specification D 3942. Unlessotherwise noted, the unit of measurement used for unit cell size hereinis in Angstroms (Å).

Although the pore diameters of the cells of the pure crystalline Y-typezeolite structure are approximately 7.4 Å in diameter as defined by the12-membered zeolite ring structure, the zeolite crystals tend to containdefects in the overall structure which act as large pore structures orlarge pore (i.e., mesoporous) diameters. These larger pore structurespossessed by the Y-type zeolites can be beneficial in providing sizeselective cracking sites in many industrial processes. Certainmesoporous pore structures (in particular those between 50 and 500 Å indiameter) can be beneficial to certain petroleum refining orpetrochemical conversion processes such as, but not limited to,catalytic cracking, fluidized catalytic cracking, hydrocracking,hydrodesulfurization, reforming, alkylation, oligomerization, dewaxing,and isomerization.

One common use of Y-type zeolites is as a catalytic component in a typeof fluid catalytic cracking process for conversion of hydrocarbonprocess feedstreams that contain a substantial amount of hydrocarbons inthe gas oil and heavier boiling point range (boiling ranges of about 450to about 1050° F.) into lighter fuel products, in particular gasolines,naphthas, and distillates. This petroleum refinery process is commonlytermed as “Fluid Catalytic Cracking” or “FCC” and utilizes azeolite-containing cracking catalyst that is fluidized prior tocontacting the hydrocarbon process feedstream to the FCC unit. TheY-type zeolites, and in particular the Ultra Stable Y (“USY”) zeolites,are particularly useful in these processes due to their high activityand selectivity to gasoline products as well as their strong surfacearea stability in the presence of high temperature steam.

As demand for crude supplies and feedstocks to petroleum refineries andpetrochemical plants has increased, there has been a greater incentiveto process heavier, higher molecular weight feedstreams in many of theassociated separation and conversion units. In particular, as theoverall feed compositions trend toward heavier molecular weighthydrocarbon feedstreams, it continues to become more desirable tocatalytically crack these heavier feeds (also termed “bottoms cracking”)to convert more of these components into high value liquid products.

As discussed, the Y-type zeolites, in particular the Ultrastable Y(“USY”) zeolites, are a preferred zeolitic component in many catalystsdue to their acidic cracking activity, their 3-dimensional structure,their high surface area hydrothermal stability, and their relatively lowcost production. The ultrastable versions of the Y-zeolites areparticularly preferred for fluid catalytic cracking applications due totheir high resistance to degradation in the presence of high temperaturesteam (above about 1200° F.). Conventional USY zeolites are prepared bysteam calcination of a partially ammonium-exchanged Na—Y zeolite atnominal temperatures of 1000-1200° F. The resulting USY zeolitestypically exhibit a unit cell size in the range of about 24.50 to about24.58 Å.

These conventional USY zeolites contain a significant volume associatedwith pores in the range of 30 to 50 Å diameter, which are easilyobserved by a standard nitrogen adsorption-desorption test asinterpreted by the BJH method. FIG. 1 shows a typical the BJH N₂Desorption Plot of a typical USY zeolite. As can be seen in FIG. 1, theUSY exhibits a high volume of pores in the “small mesoporous” range (30to 50 Å pore diameter) as well as a significant “small mesopore peak” inthe BJH N₂ Desorption Plot of about 0.20 cm³/g or more in this smallmesopore range. This high peak in the 30 to 50 Å pore diameter range ofthe BJH N₂ Desorption Plot is a common feature for Y-zeolite materialsthat possess a significant pore volume in the mesoporous range (30 to500 Å pore diameters). This peak exhibited in the BJH N₂ Desorption Plotof the Y zeolites is termed herein as the “Small Mesopore Peak” of thezeolite and is defined above. Without wishing to be held to any theory,it is believed that this phenomenon occurs due to a “bottlenecking” ofsome of the mesoporous structures in the zeolite creating an ink-bottleeffect wherein a significant amount of the nitrogen inside the internalpore cavities cannot be released during the desorption phase of the testuntil the partial pressure is reduced below the point associated withthis small mesopore peak point. Typically in a standard nitrogenadsorption/desorption test this peak is associated at a point in thedesorption branch at a relative nitrogen pressure (P/P_(o)) of about 0.4to about 0.45. See “Characterization of Porous Solids and Powders:Surface Area, Pore Size and Density”, by Lowell, S., Shields, J. E.,Thomas, M. A., and Thommes, M., pp. 117-123, (Springer, Netherlands2006), which is incorporated herein by reference.

As can further be seen in FIG. 1, there is no significant “largemesopore peak” associated with the large mesoporous structure (50 to 500Å pore diameter range) of the USY zeolite. The USY sample of thisexample is further described in Example 1. While USY zeolites do notpossess a significant volume of large mesopores (in the 50 and 500 Ådiameter range) upon fabrication, they may develop these large mesoporesupon steaming at high temperatures. A common test in the industry is tocontact the zeolite with a high temperature steam (for example, 100%partial pressure steam at 1400° F. for 16 hours) to determine thehydrothermal stability of the zeolite. This test is designed to simulatethe steaming conditions of a FCC unit Wherein the catalysts aretypically exposed to steam at elevated temperatures. The main reason forthis test is to determine the ability of the zeolite to retain surfacearea when exposed to steam at high temperatures. However, upon severesteaming, Y-type zeolites also tend to increase the pore volumeassociated with the large mesopores, and the surface area of the zeolitetends to diminish as the steaming conditions become more severe.

According to the details of Example 1, a conventional USY sample asdescribed above and shown in FIG. 1 was further ammonium ion-exchangedthree times and then steamed at 1400° F. for 16 hours to determine theresulting pore distribution and surface area stability of the USYzeolite under these hydrothermal conditions. FIG. 2 shows the BJH N₂Desorption Plot of the ion-exchanged USY zeolite after long-termdeactivation steaming. As can be seen from FIG. 2, the steamed USYdevelops a “large mesopore peak” in the large mesoporous structures (50to 500 Å pore diameter range) of the zeolite. However, as also can beseen in FIG. 2, the “small mesopore peak”, associated with pores in the30 to 50 Å pore diameter range of the steamed USY, is riot significantlydecreased as compared to the small mesopore peak of the un-steamed USYsample as shown in FIG. 1. Here, the small mesopore peak of the steamedUSY is about 0.19 cm³/g.

While not wishing to be held to any theory, it is believed that thesmall and large mesoporous pore structures of the zeolite are created bydefects and/or deterioration of the zeolite crystalline structure,thereby creating structural defect voids (or equivalent “pores”) thatare larger in size than those of the as-synthesized (pure crystal)structure of the zeolite.

What has been discovered in the present invention is a highlyhydrothermally stable Y-zeolite that has a significantly suppressedsmall mesopore peak in both the as-fabricated and as-steamed conditionswhile maintaining a high volume of large mesopores (50 to 500 Å porediameter range). In another embodiment of the present invention, is ahighly hydrothermally stable Y-zeolite that has a significantlysuppressed small mesopore peak in both the as-fabricated and as-steamedconditions while maintaining a high ratio of large-to-small mesoporousvolume. The zeolite of this invention is termed herein as an “ExtraMesoporous Y” (or “EMY”) zeolite.

In an embodiment of the EMY zeolite of the current invention, thestarting material is a conventional Na—Y type zeolite with a sodiumoxide (Na₂O) content of about 10 to 15 wt %. In an embodiment of thepresent invention, tire EMY zeolite precursor is ammonium-exchanged tolower the Na₂O content to a desired level for the production of an EMYzeolite. Generally, about one to about three ammonium-exchanges arerequired to reduce the Na₂O content of a typical Na—Y precursor to adesired level for the production of an EMY zeolite. Based on fabricationtesting, it is believed by the inventor at this time that the sodiumlevel of the EMY precursor must be maintained in certain ranges in orderto obtain an EMY zeolite. In a preferred embodiment of the presentinvention, the Na₂O content of the ammonium-exchanged Na—Y zeoliteprecursor is brought to about 2.0 to about 5.0 wt % Na₂O. Morepreferably, the Na₂O content of the ammonium-exchanged Na—Y zeoliteprecursor is brought to about 2.3 to about 4.0 wt % Na₂O. In thispreferred embodiment, it is believed that the number of ion-exchangesteps performed is not essential to the formation of EMY as long as theNa₂O content of the EMY precursor is within a desired range. Unlessotherwise noted, the Na₂O content is as measured on the zeoliteprecursor prior to high temperature steam calcination and reported on adry basis.

The EMY precursors or the final EMY zeolite may also be rare earthexchanged to obtain a rare earth exchanged EMY or “RE-EMY” zeolite. Thezeolites may be rare earth exchanged in accordance with any ion-exchangeprocedure known in the art. It should also be noted that the weightpercentages used herein are based on the dry weight of the zeolitematerials.

The ammonium-exchanged Na—Y precursor thus obtained is subjected to avery rapid high temperature steam calcination. In this high temperaturesteam calcination process, the temperature of the steam is from about1200 to about 1500° F. More preferably the temperature of the steam isfrom about 1200 to about 1450° F., more preferably from about 1250 toabout 1450° F., and even more preferably from about 1300 to about 1450°F. These high temperature steam calcination temperatures for theproduction of an EMY zeolite are generally higher than those used in theproduction of conventional USY zeolites which are high temperature steamcalcined at temperatures from about 1000 to about 1200° F. and do notundergo the rapid heating in the high temperature calcination step asthe EMY zeolites of the present invention.

It has been discovered that it is important in achieving the EMY zeolitestructure that the zeolite precursor be brought up close to the desiredsteaming temperature in a very rapid manner. The temperature of thezeolite during the steaming process may be measured by a thermocoupleimplanted into the bed of the EMY zeolite precursor.

In a preferred embodiment of making the EMY zeolite of the presentinvention, the temperature of the zeolite is raised from a standardpre-calcination temperature to within 50° F. (27.8° C.) of the steamtemperature during the high temperature steam calcination step in lessthan about 5 minutes, hi a more preferred embodiment of making the EMYzeolite of the present invention, the temperature of the zeolite israised from a standard pre-calcination temperature to within 50° F.(27.8° C.) of the steam temperature during the high temperature steamcalcination step in less than about 2 minutes.

Although not critical to the fabrication process and not so limited asto the claimed invention herein, typically the pre-calcinationtemperature in a Y-type zeolite manufacturing process is from about 50°F. to about 300° F. Although not wishing to be held to any theory, it isbelieved that if the EMY precursor is held at temperatures above about300° F. prior to rapid high temperature steam calcination, thatformation of a final EMY material may be hindered.

Example 2 herein describes the synthesis of one embodiment of an ExtraMesoporous Y (“EMY”) zeolite. FIG. 3 shows the BJH N₂ Desorption Plot ofthe EMY zeolite sample from Example 2 prior to additional ammoniumexchange and long-term deactivation steaming. As can be seen in FIG. 3,the EMY zeolite exhibits a very low volume of pores in the “smallmesoporous” range (30 to 50 Å pore diameter) as well as a very low“small mesopore peak” of about 0.09 cm³/g in this small mesopore range.In comparing FIG. 1 (USY zeolite) and FIG. 3 (EMY zeolite) it should benoted that this “small mesopore peak” has been substantially depressedin the EMY zeolite. It can be seen in FIG. 1 that this small mesoporepeak is about 0.20 cm³/g for the USY as compared to the small mesoporepeak of about 0.09 cm³/g for the EMY as shown in FIG. 3.

As can further be seen in FIG. 3, there is beneficially a significant“large mesopore peak” associated mainly with the large mesoporousstructures (50 to 500 Å pore diameter range) of the EMY zeolite.Comparing this to the BJH N₂ Desorption Plot of the USY zeolite in FIG.1, it can be seen that the EMY zeolite in FIG. 3 exhibits a significantlarge mesopore peak of about 0.19 cm³/g whereas the USY zeolite in FIG.1 shows no significantly comparable large mesopore peak in this range.

The pore volumes in each of the ranges, 30 to 50 Angstroms as well as 50to 500 Angstroms were determined by utilizing the pore volume data fromthe BJH N₂ Desorption tests and interpolating the data to the necessaryendpoints. This method for calculating the pore volumes is explained indetail in Example 1 and the same method for calculating the pore volumeswas utilized throughout all examples herein. The method as describedtherein defines how to interpret and calculate the pore volume values ofthe zeolites within each of the defined pore diameter ranges.

The “small mesopore” and “large mesopore” pore volumes and the BETsurface areas for the USY and EMY zeolites of FIGS. 1 and 3,respectively, were measured and are shown in Table 1 as follows:

TABLE 1 Zeolite Properties prior to Long-Term Steaming Small (30- Large(50- Large-to- Small 50 Å) 500 Å) Small Mesopore BET Unit MesoporeMesopore Pore Peak, Surface Cell Volume Volume Volume dV/dlogD Area SizeZeolite (cm³/g) (cm³/g) Ratio (cm³/g) (m²/g) (Å) USY 0.0193 0.0195 1.010.20 811 24.55 (FIG. 1) EMY 0.0109 0.0740 6.79 0.09 619 24.42 (FIG. 3)

It should be noted that FIGS. 1 and 3, as well as the data in Table 1,reflect the USY and EMY zeolite samples after the high temperature steamcalcination step and prior to any subsequent treating. As can be seen inTable 1, the volume of small mesopores is larger in the USY zeolite thanin the EMY zeolite. However, it can also be seen that the volume oflarge mesopores in the EMY zeolite is significantly larger than thevolume of large mesopores in the USY zeolite. As discussed, it isdesired to lower the amount of pore volume in the small mesopore rangeand increase the amount of pore volume in the large mesopore range ofthe zeolite. Therefore, an important characteristic of the zeolite isthe ratio of the large mesopore volume (“LMV”) to the small mesoporevolume (“SMV”) of the subject zeolite. We term this ratio of the LMV:SMVas the “Large-to-Small Pore Volume Ratio” or “LSPVR” of the zeolite.

As can be seen from Table 1, the Large-to-Small Pore Volume Ratio or“LSPVR” of the sample USY zeolite is about 1.01 wherein the LSPVR of thesample EMY zeolite is about 6.79. This is a significant shift in theLarge-to-Small Pore Volume Ratio obtained by the present invention. In apreferred embodiment, the LSPVR of the EMY is at least about 4.0, morepreferably at least about 5.0, and even more preferably, the LSPVR ofthe EMY is at least about 6.0 immediately after the first hightemperature steam calcination step as described herein.

Additionally, the EMY zeolites of the present invention may be used inprocesses that are not subject to exposure to high temperaturehydrothermal conditions. It can be seen from Table 1, that one of theremarkable aspects of the EMY zeolites of the present invention is thatthey exhibit very high Large Mesopore Volumes as compared to thecomparable USY of the prior art. This characteristic of the EMY zeolitesof the present invention can be valuable to many commercial processes.In preferred embodiments, the as-fabricated EMY zeolites of the presentinvention have a Large Mesopore Volume of at least 0.03 cm³/g, morepreferably at least 0.05 cm³/g, and even more preferably at least 0.07cm³/g.

As utilized herein, the term “as-fabricated” is defined as the zeoliteobtained after the high temperature steam calcination step. As is knownto one of skill in the art, the “long-term deactivation steaming”referred to herein is generally utilized as a tool to test the abilityof the as-fabricated zeolite to withstand hydrothermal conditions and isnot considered as a part of the fabrication of the zeolite.

It should also be noted that it is obvious to those of skill in the artthat long-term deactivation steaming will tend to increase the LargeMesopore Volume of typical Y zeolites. However, this unusual aspect ofthe EMY zeolites of the present invention of possessing such asignificantly increased Large Mesopore Volume prior to long-termdeactivation steaming can be useful in processes wherein hightemperature hydrothermal conditions are not present or even moreimportantly in processes wherein it is undesired for the fabricatedzeolite to be long-term steam deactivated. The as-fabricated EMY zeolitepossesses higher BET surface areas as compared to the BET surface areasafter the log-term steam deactivation and the as-fabricated EMY zeolitemay be more stable in some applications than that the EMY zeoliteobtained after long-term steam deactivation.

It can also be seen from comparing FIG. 1 (USY zeolite sample) and FIG.3 (EMY zeolite sample) that the small mesopore peak in the 30 to 50 Åpore diameter range is significantly lower for the EMY zeolite than theUSY zeolite. In a preferred embodiment, the as-fabricated EMY zeoliteobtained following the high temperature steam calcination exhibits aSmall Mesopore Peak of less than about 0.15 cm³/g. In a more preferredembodiment, the EMY zeolite has a Small Mesopore Peak of less about 0.13cm³/g, and in an even more preferred embodiment, the Small Mesopore Peakof the EMY is less than about 0.11 cm³/g. The Small Mesopore Volume Peakas defined prior is the maximum value (or peak) of the pore volume value(dV/d log D, y-axis) exhibited on the BJH N₂ Desorption Plot in the 30to 50 Angstroms (Å) pore diameter range.

In addition, the EMY materials of the present invention exhibit smallerunit cell sizes as compared to similar USY materials that have undergonea single high temperature steam calcination step. As can be seen inTable 1, the USY zeolite of Example 1 has a unit cell size of about24.55 Å, while the EMY zeolite prepared from similar starting materialshas a significantly lower unit cell size of about 24.42 Å.

It has been discovered that in preferred embodiments, theseas-fabricated EMY zeolites exhibit unit cell size ranging from about24.37 to about 24.47 Å after the first high temperature steamcalcination step as described herein. In even more preferredembodiments, the as-fabricated EMY zeolites will have a unit cell sizeranging from about 24.40 to about 24.45 Å after the first hightemperature steam calcination step as described herein. This smallerunit cell size generally results in a more stable zeolite configurationdue to the higher framework silica/alumina ratios reflected by the lowerunit cell sizes of EMY zeolite.

The USY zeolite sample as described in Example 1 and shown in the BJH N₂Desorption Plot of FIG. 1 as well as the EMY zeolite sample as describedin Example 2 and shown in the BJH N₂ Desorption Plot of FIG. 3 werefurther ammonium ion-exchanged and then long-term deactivation steamedat 1400° F. for 16 hours to determine the long-term hydrothermalstability of the USY and EMY zeolites. FIG. 2 shows the BJH N₂Desorption Plot of the ion-exchanged USY zeolite of the prior art afterlong-term deactivation steaming. FIG. 4 shows the BJH N₂ Desorption Plotof the ion-exchanged EMY zeolite of an embodiment of the presentinvention after long-term deactivation steaming. As can be seen fromFIG. 4, the Large Mesopore Peak of the EMY zeolite increased desirablyfrom about 0.19 cm³/g (as shown in FIG. 3) to about 0.36 cm³/g (as shownin FIG. 4) after long-term deactivation steaming. Just as desirable,following long-term deactivation steaming of the EMY zeolite, the SmallMesopore Peak of the EMY zeolite was not significantly increased. TheSmall Mesopore Peak of the EMY zeolite remained essentially constant atabout 0.10 cm³/g (as shown in FIGS. 3 and 4).

In contrast, in the comparative USY zeolite of the prior art, the SmallMesopore Peak remained undesirably high at about 0.19 cm³/g afterlong-term deactivation steaming (see FIG. 2).

The physical properties of the zeolites obtained after long-termdeactivation steaming in Examples 1 and 2 are tabulated in Table 2below. In Table 2 below, are shown the “Small Mesopore Volumes”, the“Large Mesopore Volumes, the “Large-to-Small Pore Volume Ratios”, andthe Small Mesopore Peaks” for the USY and EMY zeolites illustrated inFIGS. 2 and 4, respectively, as well as the associated BET surface areasand the unit cell sizes as measured following three ammoniumion-exchanges and long-term deactivation steaming at 1400° F. for 16hours.

TABLE 2 Zeolite Properties after Long-Term Deactivation Steaming Small(30- Large (50- Large-to- Small 50 Å) 500 Å) Small Mesopore BET UnitMesopore Mesopore Pore Peak, Surface Cell Volume Volume Volume dV/dlogDArea Size Zeolite (cm³/g) (cm³/g) Ratio (cm³/g) (m²/g) (Å) USY 0.01120.1211 10.85 0.19 565 24.27 (FIG. 2) EMY 0.0077 0.1224 15.97 0.10 58724.27 (FIG. 4)

Another benefit of the EMY zeolites of the present invention is surfacearea stability. As can be seen in Table 2, the BET surface area for thelong-term deactivation steamed EMY zeolite sample was greater than theBET surface area for the USY sample. Additionally, the EMY retained ahigher percentage of the surface area after the three ammonium ionexchanges and long-term deactivation steaming at 1400° F. for 16 hours.Comparing Table 1 and Table 2, the USY retained about 70% of itsoriginal surface area wherein the EMY retained about 95% of its originalsurface area, indicating the superior hydrostability of the EMY zeolitesof the present invention. In preferred embodiments of the presentinvention, the EMY zeolite has BET Surface Area of at least 500 m²/g asmeasured either before long-term deactivation steaming at 1400° F. for16 hours or after long-term deactivation steaming at 1400° F. for 16hours.

In a preferred embodiment, the “Large-to-Small Pore Volume Ratio” (or“LSPVR”) of the EMY is at least about 10.0, more preferably at leastabout 12.0, and even more preferably, the LSPVR of the EMY is at leastabout 15.0 after long-term deactivation steaming at 1400° F. for 16hours.

Example 3 shows the differing effects of varying the high temperaturesteam calcination temperature in attempting to fabricate an EMY zeolite.The details of the precursor and the high temperature steam calcinationsteps are explained further in Example 3. The BJH N₂ Desorption Plotsfor the six zeolite samples (labeled samples 3A through 3F) in Example 3are shown respectively in FIGS. 5 through 10. Table 3 below alsotabulates some of the important characteristics of the zeolite productsobtained from the testing in this Example.

TABLE 3 Zeolite Properties from Samples 3A through 3F of Example 3Large- Small (30- Large (50- to- Small BET 50 Å) 500 Å) Small MesoporeSur- Unit Mesopore Mesopore Pore Peak, face Cell Zeolite Volume VolumeVolume dV/dlogD Area Size Sample (cm³/g) (cm³/g) Ratio (cm³/g) (m²/g)(Å) Sample 0.0088 0.0200 2.27 0.09 934 N/A 3A (FIG. 5) Sample 0.02070.0327 1.58 0.16 865 24.54 3B (FIG. 6) Sample 0.0157 0.0510 3.25 0.11786 24.49 3C (FIG. 7) Sample 0.0119 0.0542 4.55 0.11 774 24.47 3D (FIG.8) Sample 0.0095 0.0722 7.58 0.09 745 24.45 3E (FIG. 9) Sample 0.01470.0899 6.12 0.21 518 24.42 3F (FIG. 10)

As can be seen in Table 3, the precursor (Sample 3A) has no severe SmallMesopore Peak in the 30 to 50 Å pore diameter range, and no significantLarge Mesopore Peak (see FIG. 5) in the 50 to 500 Å pore diameter range.This precursor (unsteamed) Sample 3A is used as a basis for comparisonof the other Samples 3B through 3F. When the precursor was hightemperature steam calcined in Sample 3B with a 100% partial pressuresteam at 1000° F. for one hour, the zeolite experienced an increase inthe Small Mesopore Peak in the 30 to 50 Å range (from 0.09 cm³/g to 0.16cm³/g), and there was not a significant Large Pore Volume increase (seeFIG. 6). This sample did not meet the characteristics necessary for theEMY zeolite of the present invention.

The precursor of Sample 3C was high temperature steam calcined with a100% partial pressure steam at 1200° F. for one hour. The zeoliteobtained under the conditions of Sample 3C experienced a significantdecrease in the Small Mesopore Peak in the 30 to 50 Å pore diameterrange as compared to Sample 3B (from 0.16 cm³/g to 0.11 cm³/g) as wellas a simultaneous significant increase in the Large Mesopore Volume (seeFIG. 7, as well as Table 3). This sample was within the desiredcharacteristics of the preferred embodiments of the EMY zeolites of thepresent invention.

The precursor of Sample 3D was high temperature steam calcined with a100% partial pressure steam at 1300° F. for one hour. Here it can beseen in Table 3 as well as FIG. 8, that the zeolite obtained experienceda similar decrease in the Small Mesopore Peak in the 30 to 50 Å porediameter range as compared to Sample 3B. However, more importantly, theLarge Mesopore Volume of Sample 3D increased significantly as comparedto Samples 3B and 3C (see FIG. 8, as well as Table 3). As can be seen inTable 3, the Large-to-Small Pore Volume Ratio (“LSPVR”) increased toapproximately 4.55 as is desired in the EMY zeolites of the presentinvention.

The desired characteristics of the EMY zeolite were even more pronouncedin Sample 3E. In Sample 3E, precursor was high temperature steamcalcined with a 100% partial pressure steam at 1400° F. for one hour. Inreviewing Table 3 and FIG. 9, it can be seen that the Large MesoporeVolume was further increased as compared to the prior samples and alsoimportantly, the Large-to-Small Pore Volume Ratio (“LSPVR”) increased to7.58 in the final zeolite as is desirable. In addition, it can be seenthat the Small Mesopore Peak for Sample 3E (FIG. 9) was further reducedto 0.09 cm³/g, within the limitations of the more preferred embodimentsof the EMY zeolites of the present invention.

Lastly from the samples of Example 3, FIG. 10 shows the BJH N₂Desorption Plot for the zeolite obtained from the precursor in Sample 3Fwhich was high temperature steam calcined with a 100% partial pressuresteam at 1500° F. for 1 hour. Here it can be seen that the productzeolite appears to have more degradations at the high temperature steamcalcination temperature. Although the Large Mesopore Volume was furtherincreased in the zeolite, the Small Mesopore Peak was also increased forthe Sample 3F (FIG. 10). The value of this Small Mesopore Peak forSample 3F (0.21 cm³/g) exceeds the limitations of the embodiments of theEMY zeolites.

In a preferred embodiment of the present invention, the Y zeolite of thepresent invention (i.e., “EMY”) is utilized in a process for convertinga hydrocarbon-containing feedstream, comprising:

a) contacting the hydrocarbon-containing feedstream with the Y zeolitein a petroleum refining process; and

b) producing at least one product stream which has a lower averagemolecular weight than the hydrocarbon-containing feedstream;

wherein the zeolite has a Large Mesopore Volume of at least about 0.03cm³/g and a Small Mesopore Peak of less than about 0.15 cm³/g.

In a preferred embodiment, the EMY zeolite of the present invention isutilized in a petroleum refining or petrochemical conversion processesselected from catalytic cracking, fluidized catalytic cracking,hydrocracking, hydrodesulfurization, reforming, alkylation,oligomerization, dewaxing, and isomerization. In a preferred embodiment,the EMY zeolite of the present invention is utilized in a catalyticcracking process. In a more preferred embodiment, the EMY zeolite of thepresent invention is utilized in a fluidized catalytic cracking process.

Although the present invention has been described in terms of specificembodiments, it is not so limited. Suitable alterations andmodifications for operation under specific conditions will be apparentto those skilled in the art. It is therefore intended that the followingclaims be interpreted as covering all such alterations and modificationsas fall within the true spirit and scope of the invention.

The Examples below are provided to illustrate the manner in which theEMY zeolites of the current invention were synthesized and illustratethe improved product qualities and the benefits from specificembodiments of the current invention this obtained. These Examples onlyillustrate specific embodiments of the present invention and are riotmeant to limit the scope of the current invention.

EXAMPLES Example 1

A commercial ammonium-exchanged Y zeolite with a low sodium content(CBV-300® from Zeolyst™, SiO₂/Al₂O₃ molar ratio=5.3, Na₂O 3.15 wt % ondry basis) was steamed in a horizontal calcination oven which was at atemperature of 1000° F. and in a flow of 50% steam+50% N₂ for 1 hour.The resulting product was an ultra-stable Y (USY) zeolite, and wasanalyzed with a Micromeritics® Tristar 3000® analyzer to determine thepore size distribution characteristics by nitrogen adsorption/desorptionat 77.35° K. The BJH method as described in the specification wasapplied to the N₂ adsorption/desorption isotherms to obtain the poresize distribution of the zeolite, and a plot of dV/d log D vs. AveragePore Diameter is shown in FIG. 1.

A copy of the pertinent data generated by the BJH method generated fromthe N₂ adsorption/desorption isotherms for this zeolite sample isreproduced in Table 4 below. This test method and the associated formatof data generated as presented are familiar to one of skill in the art.

TABLE 4 BJH Pore Volume Distribution of USY Sample

As can be seen in Table 4, a calculated Cumulative Pore Volume (cm³/g)is associated with a range of Pore Diameter (nm) as the testincrementally desorbs the nitrogen from the test sample. An IncrementalPore Volume is then calculated for each of these ranges. A pore volumewithin a certain range (for example a range from 50 to 500 Å, which isequivalent to 5 to 50 nm as presented in Table 4) can be calculated bysubtracting the Cumulative Pore Volume at 50 nm from the Cumulative PoreVolume at 5 nm. Where necessary, the Cumulative Pore Volume at aspecific pore size can be calculated by interpolating the data withinthe range. This method was utilized for all of the Examples herein.

For example, to determine the total pore volume associated with porediameters between 5 nm and 50 nm, first the Cumulative Pore Volumeassociated with 50 nm was calculated by interpolating the amount of theIncremental Pore Volume (highlighted) associated with the differencebetween 62.8 nm and 50.0 nm in the 62.8 to 41.5 nm pore diameter rangeas shown in the table (highlighted) and adding this amount to theCumulative Pore Volume (highlighted) from the prior range. Thecalculation for the Cumulative Pore Volume associated with 50 nm porediameter was calculated from the data in Table 4 above as follows:((62.8−50.0)/(62.8−41.5)*0.0032)+0.0085=0.0104 cm³/g

The calculation is then performed similarly for the Cumulative PoreVolume associated with 5 nm pore diameter. The calculation was asfollows:((5.3−5.0)/(5.3−4.6)*0.0031)+0.0286=0.0299 cm³/g

The total Pore Volume associated with the pore diameter ranges of 5 nmto 50 nm (50 Å to 500 Å) of the USY of this example is thus equal to thedifference in the Cumulative Pore Volumes associated with 5 nm and 50 nmrespectfully as follows:0.0299 cm³/g−0.0104 cm³/g=0.0195 cm³/g

This value is the Large Mesopore Volume for this USY sample as shown inTable 1. All other pore volumes associated with specific pore diameterranges can be and were calculated herein by the same basic method.

As such, the following properties of this USY zeolite were obtained fromthe data:

Small Mesoporous Volume (Range: 3.0 nm to 5.0 nm): 0.0193 cm³/g

Large Mesoporous Volume (Range: 5.0 nm to 50.0 nm,): 0.0195 cm³/g

Ratio of (Large Mesopore Volume)/(Small Mesopore Volume): 1.01

Small Mesopore Peak (dV/d log D@3.9 nm): 0.20 cm³/g

Additionally, the USY zeolite sample exhibited a BET surface area of 811m²/g, and a unit cell size of 24.55 angstroms.

A sample of the prepared USY zeolite above was further subjected to anammonium ion-exchange consisting of adding 80 grams of the zeolite into800 ml of NH₄NO₃ (1M) solution at 70° C. and agitating for 1 hour,followed by filtration on a funnel and washing the filter cake with 1000ml of de-ionized water. The water rinsed zeolite cake was dried on thefunnel by pulling air through, then in an oven at 120° C. in air forover 2 hours, Chemical analysis of the dried zeolite by ICP showed 0.48wt % Na₂O (dry basis). A Na₂O content of about 0.50 wt % was targeted.The dried zeolite was subjected to long-term deactivation steaming at1400° F. for 16 hours, 100% steam, to determine its hydrothermalstability.

The zeolite Obtained after long-term deactivation steaming was similarlyanalyzed in a Micromeritics® Tristar 3000® analyzer. The BJH method wasapplied to the N₂ adsorption/desorption isotherms to obtain the poresize distribution of the zeolite, and a plot of dV/d log D vs. AveragePore Diameter is shown in FIG. 2. The following properties of thislong-term deactivation steamed USY zeolite were obtained from the data:

Small Mesoporous Volume (Range: 3.0 nm to 5.0 nm): 0.0112 cm³/g

Large Mesoporous Volume (Range: 5.0 nm to 50.0 nm,): 0.1211 cm³/g

Ratio of (Large Mesopore Volume)/(Small Mesopore Volume): 10.85

Small Mesopore Peak (dV/d log D@3.9 nm): 0.19 cm³/g

Additionally, the USY zeolite after long-term deactivation steamingexhibited a BET surface area of 565 m²/g, and a unit cell size of 24.27angstroms.

Example 2

In this example, an embodiment of the Extra Mesoporous Y (“EMY”) zeolitewas prepared as follows:

The same commercial ammonium-exchanged Y zeolite (CBV-300®) with a lowsodium content (SiO₂/Al₂O₃ molar ratio=5.3, Na₂O 3.15 wt % on dry basis)as in Example 1 was placed in a horizontal quartz tube, which wasinserted into a horizontal oven pre-equilibrated at 1400° F. in 100%steam at atmospheric pressure. Utilizing this procedure, the temperatureof the zeolite precursor was raised to within 50° F. of the hightemperature steam calcination temperature (i.e., to 1350° F.) within 5minutes. The steam was let to pass through the zeolite powders. After 1hour, the tube was removed from the horizontal oven and resulting EMYzeolite powders were collected. It should be noted that the startingmaterial (i.e., the EMY precursor zeolite) selected was a low sodiumcontent Y zeolite. As described in the specification above, it isbelieved that production of the EMY zeolite is dependent upon the properzeolite sodium content prior to high temperature steam calcination. Ifthe sodium content is not within the specifications as described herein,the starting Y zeolite may first require ammonium-exchange or methods asknown in the art to reduce the sodium content of the EMY zeoliteprecursor to acceptable levels prior to high temperature steamcalcination to produce the EMY zeolite.

The resulting EMY zeolite was analyzed by a Micromeritics® Tristar 3000®analyzer as used in Example 1. The BJH method as described in thespecification was applied to the N₂ adsorption/desorption isotherms toobtain the pore size distribution of the zeolite, and a plot of dV/d logD vs. Average Pore Diameter is shown in FIG. 3. The following propertiesof this EMY zeolite were obtained:

Small Mesoporous Volume (Range: 3.0 nm to 5.0 nm): 0.0109 cm³/g

Large Mesoporous Volume (Range: 5.0 nm to 50.0 nm,): 0.0740 cm³/g

Ratio of (Large Mesopore Volume)/(Small Mesopore Volume): 6.79

Small Mesopore Peak (dV/d log D@3.9 nm): 0.09 cm³/g

Additionally, the EMY zeolite sample exhibited a BET surface area of 619m²/g, and a unit cell size of 24.42 angstroms.

A sample of the EMY zeolite above was further subjected to an ammoniumion exchange consisting of adding 100 grams of the EMY zeolite into 1000ml of NH₄NO₃ (1M) solution at 70° C. and agitating for 1 hour, followedby filtration on a funnel and washing the filter cake with 1000 ml ofde-ionized water. The water rinsed zeolite cake was dried on the funnelby pulling air through, then in an oven at 120° C. in air for over 2hours. The ammonium ion exchange was repeated using 60 g of the washedEMY zeolite in 600 ml of NH₄NO₃ (1M) solution at 70° C. and agitatingfor 1 hour, followed by filtration on a funnel and washing the filtercake with 1000 ml of de-ionized water. The water rinsed zeolite cake wasdried on the funnel by pulling air through, then in an oven at 120° C.in air for over 2 hours. Chemical analysis of the dried zeolite by ICPshowed 0.64 wt % Na₂O (dry basis). A Na₂O content of about 0.50 wt % wastargeted. This zeolite was then subjected to long-term deactivationsteaming at 1400 for 16 hours, 100% steam, to determine its hydrothermalstability.

The EMY zeolite obtained after long-term deactivation steaming was alsoanalyzed by a. Micromeritics® Tristar 3000® analyzer. The BJH method wasapplied to the N₂ adsorption/desorption isotherms to obtain the poresize distribution of the zeolite, and a plot of dV/d log D vs. AveragePore Diameter is shown in FIG. 4. The following properties of the EMYzeolite after long-term deactivation steaming were thus obtained fromthe data:

Small Mesoporous Volume (Range: 3.0 nm to 5.0 nm): 0.0077 cm³/g

Large Mesoporous Volume (Range: 5.0 nm to 50.0 nm,): 0.1224 cm³/g

Ratio of (Large Mesopore Volume)/(Small Mesopore Volume): 15.97

Small Mesopore Peak (dV/d log D@3.9 nm): 0.10 cm³/g

Additionally, the surface area of the EMY zeolite after long-termdeactivation steaming was analyzed by a BET Test. The zeolite exhibiteda BET surface area of 587 m²/g, and a unit cell size of 24.27 angstroms.

Example 3

In this example, the same ammonium-exchanged commercial Y zeoliteCBV-300® as in Example 1 and 2 was subjected to differing hightemperature steam calcining steps as follows and each of the resultingSamples 3A through 3F were analyzed using a Micromeritics® Tristar 3000®analyzer similar to Examples 1 and 2.

Sample 3A is the starting Y zeolite (CBV-300 precursor as in Examples 1and 2. The BJH N₂ Desorption Plot for Sample 3A is shown in FIG. 5.

Sample 3B was obtained by subjecting the starting Y zeolite precursor ofSample 3A to high temperature steam calcination at 1000° F. for 1 hourin 100% steam, The temperature during the high temperature steamcalcination was raised to within 50° F. of the high temperature steamcalcination temperature within 2 minutes. The BJH N₂ Desorption Plot forSample 3B is shown in FIG. 6.

Sample 3C was obtained by subjecting the starting Y zeolite precursor ofSample 3A to high temperature steam calcination at 1200° F. for 1 hourin 100% steam. The temperature during the high temperature steamcalcination was raised to within 50° F. of the high temperature steamcalcination temperature within 2 minutes. The BJH N₂ Desorption Plot forSample 3C is shown in FIG. 7.

Sample 3D was obtained by subjecting the starting Y zeolite precursor ofSample 3A to high temperature steam calcination at 1300° F. for 1 hourin 100% steam. The temperature during the high temperature steamcalcination was raised to within 50° F. of the high temperature steamcalcination temperature within 2 minutes. The BJH N₂ Desorption Plot forSample 3D is shown in FIG. 8.

Sample 3E was obtained by subjecting the starting Y zeolite precursor ofSample 3A to high temperature steam calcination at 1400° F. for 1 hourin 100% steam. The temperature during the high temperature steamcalcination was raised to within 50° F. of the high temperature steamcalcination temperature within 2 minutes. The BJH N₂ Desorption Plot forSample 3E is shown in FIG. 9.

Sample 3F was obtained by subjecting the starting Y zeolite precursor ofSample 3A to high temperature steam calcination at 1500° F. for 1 hourin 100% steam. The temperature during the high temperature steamcalcination was raised to within 50° F. of the high temperature steamcalcination temperature within 2 minutes. The BJH N₂ Desorption Plot forSample 3F is shown in FIG. 10.

The Small Mesoporous Volume (cm³/g), the Large Mesoporous Volume(cm³/g), the Small Mesopore Peak (cm³/g), as well as the Large-to-SmallPore Volume Ratio (“LSPVR”) for each of Samples 3A through 3F are shownin Table 3 herein. The BET surface area and Unit Cell Size are alsoshown in Table 3 for each of the Samples 3A through 3F.

As can be seen from FIG. 5 the zeolite Sample 3A (i.e., the startingammonium-exchanged Y zeolite (CBV-300®) had no appreciable peakassociated with the large mesoporous pore range while exhibiting a SmallMesopore Peak of about 0.09 cm³/g.

As can be seen from FIG. 6 the zeolite Sample 3B obtained after hightemperature steam calcination of the starting ammonium-exchanged Yzeolite precursor exhibited only minor Large Mesopore Peak in the 50 to500 Å pore diameter range, thereby resulting in a below desiredLarge-to-Small Pore Volume Ratio of about 1.58. Sample 3B did not quitedevelop into an EMY zeolite of the present invention, due to itsslightly higher Small Mesopore Peak (about 0.16 cm³/g) in the smallmesoporous pore range (30 to 50 Å pore diameter range).

FIG. 7 shows the BJH N₂ Desorption Plot of Sample 3C. Here thecharacteristics of an EMY zeolite begin to develop wherein the obtainedzeolite exhibits a significantly increased Large Mesopore Peak and anincreased Large Mesopore Volume. Simultaneously, both the Small MesoporePeak and the Small Mesopore Volume are decreased. The Large MesoporeVolume and the Small Mesopore Peak of Sample 3C were within the rangesof the EMY zeolite of the present invention.

FIG. 8 shows BJH N₂ Desorption Plot of Sample 3D. Here an EMY zeolitestructure is developed with an increased Large Mesopore Peak and anincreased Large Mesoporous Volume, with a simultaneous reduction of theSmall Mesoporous Peak and the Small Mesopore Volume. The Large MesoporeVolume and the Small Mesopore Peak of Sample 3D were within the rangesof the EMY zeolite of the present invention. The Large Mesopore Volumeand the Small Mesopore Peak of Sample 3D were within the ranges of theEMY zeolite of the present invention. Additionally, in this embodiment,the Large-to-Small Pore Volume Ratio increased significantly to withinthe desired preferred embodiment ranges of the EMY zeolite of thepresent invention.

FIG. 9 shows BJH N₂ Desorption Plot of Sample 3E which underwent a rapidrise high temperature steam calcination of 1400° F. for 1 hour. It canbe seen that the EMY zeolite of Sample 3E exhibits a significantlyimproved pore structure with a Large-to-Small Pore Volume Ratio(“LSPVR”) of about 7.58. As can be seen from the data in Table 3, Sample3E has the largest LSPVR of all of the samples in this comparativeexample as well as the largest Large Pore Volume (0.0722 cm³/g) of theacceptable EMY zeolites of this comparative example. Additionally, thisEMY zeolite sample maintained a very low value of the Small MesoporePeak of 0.09 cm³/g. The Large Mesopore Volume and the Small MesoporePeak of Sample 3E were within the ranges of the EMY zeolite of thepresent invention and this sample exhibited the most preferred overallcharacteristics of the EMY zeolite among the comparative samples.

In contrast to Samples 3C through 3E, the zeolite obtained in Sample 3Fwhich was subjected to high temperature steam calcination of 1500° F.for 1 hour experienced significant degradation. The BJH N₂ DesorptionPlot of Sample 3F is shown in FIG. 10. It can be seen from FIG. 10 aswell as the data presented in Table 3, that while Sample 3F maintained asignificant amount of Large Mesopore Volume, the Small Mesopore Peak ofthe zeolite obtained undesirably increased significantly to 0.21 cm³/g.Thus, Sample 3F does not meet the necessary characteristics of the EMYzeolite. Therefore, it has been found that in preferred embodiments ofthe present invention, the EMY precursor is subjected to a hightemperature steam calcination of less than about 1500° F. to obtain theEMY zeolite.

What is claimed is:
 1. A Y zeolite comprising a Large Mesopore Volume ofat least about 0.03 cm³/g and a Small Mesopore Peak of less than about0.15 cm³/g.
 2. The zeolite of claim 1, wherein the unit cell size of thezeolite is from about 24.37 Angstroms to about 24.47 Angstroms.
 3. Thezeolite of claim 1, wherein the zeolite has a Large-to-Small Pore VolumeRatio of at least about 4.0.
 4. The zeolite of claim 1, wherein theprecursor of the zeolite is subjected to a high temperature steamcalcination step at a temperature from about 1200° F. to about 1500° F.wherein the temperature of the zeolite precursor is within 50° F. of thehigh temperature steam calcination temperature in less than 5 minutes.5. The zeolite of claim 4, wherein the Na₂O content of the precursor ofthe zeolite prior to the high temperature steam calcination step is fromabout 2 to about 5 wt % of the total precursor weight on a dry basis. 6.The zeolite of claim 1, wherein the Small Mesopore Volume Peak of thezeolite is less than about 0.13 cm³/g.
 7. The zeolite of claim 6,wherein the Large Mesopore Volume of the zeolite is at least about 0.05cm³/g.
 8. The zeolite of claim 1, wherein the Large Mesopore Volume ofthe zeolite and the Small Mesopore Peak of the zeolite are measured inthe as-fabricated zeolite.
 9. The zeolite of claim 7, wherein the LargeMesopore Volume of the zeolite and the Small Mesopore Peak of thezeolite are measured in the as-fabricated zeolite.
 10. The zeolite ofclaim 3, wherein Large-to-Small Pore Volume Ratio of the zeolite is aleast about 5.0.
 11. The zeolite of claim 10, wherein the unit cell sizeof the zeolite is from about 24.40 Angstroms to about 24.45 Angstroms.12. The zeolite of claim 4, wherein the zeolite precursor is subjectedto a high temperature steam calcination step at a temperature from about1250° F. to about 1450° F. wherein the temperature of the zeoliteprecursor is within 50° F. of the high temperature steam calcinationtemperature in less than 5 minutes.
 13. The zeolite of claim 12, whereinthe Na₂O content of the precursor of the zeolite prior to the hightemperature steam calcination step is from about 2.3 to about 4 wt % ofthe total precursor weight on a dry basis.
 14. The zeolite of claim 1,wherein the zeolite is comprised of a rare-earth element.
 15. Thezeolite of claim 1, wherein the zeolite has a BET Surface Area a least500 m²/g.
 16. The zeolite of claim 1, wherein after long-termdeactivation steaming at 1400° F. for 16 hours, the zeolite has aLarge-to-Small Pore Volume Ratio of at least about 10.0, a SmallMesopore Peak of less than about 0.15 cm³/g, and a Large Mesopore Volumeof at least 0.07 cm³/g.
 17. The zeolite of claim 8, wherein the zeolitehas a Large-to-Small Pore Volume Ratio of at least about 5.0, a SmallMesopore Peak of less than about 0.13 cm³/g, and a Large Mesopore Volumeof at least 0.05 cm³/g.
 18. The zeolite of claim 17, wherein the zeolitehas a Large-to-Small Pore Volume Ratio of at least about 6.0, and aSmall Mesopore Peak of less than about 0.11 cm³/g.